Field of the Invention
The invention relates to suture anchors for securing sutures and other filamentary material to soft tissue. More particularly, the invention relates to suture anchors for securing sutures and similar filamentary material to soft tissue to reattach the soft tissue to bone. Still more particularly, the invention relates to suture anchors for knotlessly securing suture and filamentary material at a surgical site.
Description of the Prior Art
In situations where ligaments or other soft tissue are being secured to bone, a suture anchor is commonly employed. The anchor is inserted into a generally preformed hole in the bone and a suture or similar filamentary material extends from the anchor and is attached to the soft tissue to be secured to the bone. As used herein, the term “bone hole” is used interchangeably with “bone tunnel” and the term “suture” includes monofilament or multi-filament suture as well as any other metallic or non-metallic filamentary or wire-like material suitable for performing the function of a suture including both absorbable and non-absorbable materials.
Whether such surgical procedures are done open or closed, in most instances, the suture must be tied to the soft tissue so that a knot must be formed. When such procedures are done arthroscopically or endoscopically (i.e., closed), creation of a knot is somewhat difficult. As a result, knotless suture anchors have been recently developed to avoid the knot tying step.
One example of a knotless suture anchor is shown in U.S. Pat. No. 6,692,516 (West Jr. et al.), assigned to the assignee hereof and incorporated by reference herein. This patent discloses an expandable metallic knotless suture anchor, the design of which is difficult to implement with the use of non-metallic material. As used herein, the term “expandable” means the diameter of the device increases when it is deployed/anchored in the bone.
U.S. Published patent application 2005/0055052 (Lombardo et al.) discloses a knotless suture anchor which may be made of bioabsorbable material. This application is assigned to the assignee hereof and incorporated by reference herein. While the design disclosed in this reference is compatible with bioabsorbable material, the design is a press-fit design and is limited in the types of surgical procedures for which it is suitable. As used herein the term “press-fit” means the anchor is not turned into a bone tunnel and the diameter of the device is substantially the same before and after deployment/anchoring in the bone.
Some knotless suture anchors have been developed and one such example is disclosed in U.S. Pat. No. 8,663,279 (Burkhart et al.). This device consists of a two part anchor in the form of an inner implant, which receives suture attached to soft tissue to be repaired, and an outer, cannulated and threaded fixation device designed to be rotated relative to the inner implant whereby the outer device progressively advances toward the inner implant and frictionally engages the suture against the wall of the bone tunnel without the need to tie a knot. One difficulty with this type of system is the primary reliance on the quality of bone in the bone tunnel and the difficulty of gauging the relative positions of the inner and outer components when the components are engaged, thereby making it difficult to optimize the friction fit.
Therefore, the need exists for a simple to use suture anchor which secures suture without needing to tie a knot and which removes the primary dependency of suture security from bone quality.
It is an object of this invention to produce a non-metallic suture anchor suitable for knotlessly securing suture to attach a first body tissue to a second body tissue.
It is another object of this invention to produce a knotless suture anchor suitable for repairing a soft tissue tear, for example, a torn rotator cuff, and re-attaching it to bone, for example, the humeral head.
It is still another object of this invention to provide a method of determining the relative positions of the components of a knotless suture anchor in order to optimize the force with which the suture is held by the anchor. It is a further object of this invention to provide an apparatus for performing this method.
It is also an object of this invention to provide a method and apparatus for knotlessly securing a suture to a suture anchor where the quality of the fixation of the suture is independent of the quality of the bone into which the suture anchor is placed.